The present invention relates to a reed valve assembly of a two-stroke cycle engine which is installed in an intake passage of the engine to control admitance and shuttering for an intake air.
In the known art, there is provided a two-stroke cycle engine in which a fuel gas is taken into a crankcase of the engine and which employs a reed valve assembly for controlling admitance and shuttering for the fuel gas. In this meaning, it may be said that the reed valve assembly is one kind of check valve.
In a typical arrangement of the reed valve assembly, a valve chamber is formed in one portion of the crankcase and a carburetor is connected to the external end thereof. That is, the fuel gas is sucked into the crankcase through the valve chamber, in which a reed valve assembly is accommodated.
The reed valve assembly comprises a box-shaped valve body which has an opened base end portion and upper and lower surfaces provided with valve openings and converging towards the leading end thereof and a reed valve resiliently kept in contact with the valve openings of the upper and lower surfaces. The reed valve has the leading end as a free end and is fixedly secured at its base end portion to the valve body. Additionally, the reed valve assembly is so attached to the interior of the valve chamber as for the leading end portion to face the interior of the crankcase and as to close the inlet port means of a flange provided at the base end portion.
The fuel gas is adapted to be so intaken as to pass through the interior of the valve body from the intake passage and to push and open the reed valve by means of a negative pressure produced within the crankcase during the intake stroke of the engine. When a positive pressure is recovered within the crankcase, the reed valve soon closes the valve inlet port and prevent a reverse flow of the fuel gas. In that way, the reed valve assembly serves as a kind of check valve to control the opening and closing of the intake passage.
Incidentally, when observing the inflow state of the fuel gas in the reed valve assembly, one portion of the fuel gas is going to .flow out laterally from the side edges of the valve openings while most of the fuel gas flows out from the leading end portions of the reed valve. This portion is however prevented from smoothly flowing out because the side walls of the valve chamber are opposed thereto through a little clearance. Accordingly, this results in a lowering of an intake efficiency of the whole of the reed valve assembly.